str1 = "hello world"
str2 = 'hello world'
str3 = '''hello 
world'''
print(str1)
print(str2)
print(str3)
print('hel\'lo world')#\转义符
print('123---{0}---{1}---{2}'.format(4,5,6))
str1 = 'hello'
print('123---{str1}')

for i in range(0,101,2):
    print("======开始下载======")
    if i == 100:
        print("下载完成")
    else:
        str4 = "*"*(i//2)+"."*((100-i)//2)
        print(f'{i}%[{str4}]',)
